Tyrannosaurus rex vs. Giganotosaurus carolinii

[Ceratodromeus]

That's a start, i guess.

[theropod]

Jan 23, 2020 19:44:51 GMT 5 dinosauria101 said:

Alright, so here's a post from theropod that explains Tyrannosaurus pneumaticity very well. From here

The density?
Volumetric estimates have suggested higher densities for Carnosaurs than for Tyrannosaurus (Bates et al. 2009a, b, Hutchinson et al. 2011).

And the pneumaticity in T. rex is extreme:

www.paleoglot.org/files/Janensch%2047a.pdf


He also gives what is probably the reason for the differences between specimens in Hutchinson et al.:
The femur in Sue was also described as hollow, and the anterior caudals also bear pneumatic foramina.

As opposed to this, basal tetanurans have pneumatic cervicals and anterior dorsals, and perhaps dorsal ribs and posterior dorsals in some species (Holtz et al. 2004).
At least some megaraptorans developed a greater degree of pneumatisation (Aerosteon). Mapusaurus has a pneumatopore on the first sacral, but no further than that (Coria & Currie 2006), indicating the abdominal airsacks were way less extensive.

With all this, I think we can rely on the figures from Bates et al. and Hutchinson et al. (2009, 2009, 2011) for approximation.

Another way would be to use segment masses as a demonstration:
Hartman assumed the torso and neck (including the tigh) to have a specific gravity of 0.9. By comparison, the density of the thorax and tigh in Allosaurus sp. (Bates et al. 2009) was merely 0.778 with an abdominal airsack included. It seems like the 0.9kg/l put what is definitely over 60% of its mass at more than 15% too dense (T. rex was more pneumatic and the volumetric guess is conservative), so that could easily lower its overall mass by about 10% or more.
We could take this further if we had the precise volume measurements for the respective segments of course, which, sadly, we lack to date, but this makes a net density of ~0.8kg/l seem fairly plausible.

By any reasoning on the issue the new estimate certainly revises Hartman's earlier 6.4t figure for Sue, and I appreciate the clarity in this regard (also having an estimate actually based on a high-quality model closely approximating the in-vivo proportions instead of a compromise-mount or a useless regression equation).
I cannot say I'm very surprised by the result considering they were at the same density–the ratio ends up remarkably like what I had previously predicted from the lateral area measurements.

Then of course sample size still comes into this. Comparing MUCPv-95 to Sue (as Hartman already stated a comparison of specimens, not species) to compare the taxa's respective sizes is biased, just like comparing MUCPv-ch1 to Bob or Bucky-the former cannot realistically be expected to be as large an individual, the latter not as small an individual.
Bob, scaling down from Hartman's unaltered figure for sue, would be ~4.5t, and with an adjusted density as above, only ~4t.
This specimen is much smaller than the smallest Giganotosaurus (only 57-66% the size), while the largest Giganotosaurus even when disregarding the density is almost the same weight (98%), and perhaps even heavier than the largest T. rex–so by conclusion, Giganotosaurus’ size range is higher.

I wouldn't be totally sure of the thoracic width either but that's not my main point, we can be quite sure Tyrannosaurus has a comparatively broad torso. Even tough the Giganotosaurus seems excessively slender, even more so than a conservative model for Allosaurus sp. (and that altough it should be wider at least in the pictures since it had more spine curvature), the unknowns are pretty big.

References:
Bates, Karl T.; Falkingham, Peter L.; Breithaupt, Brent H.; Hodgetts, David; Sellers, William I.; Manning, Philip L.:How Big Was ‘Big Al’? Quantifying the effect of soft tissue and osteological unknowns on mass predictions for Allosaurus (Dinosauria: Theropoda). Palaeontologia Electronica, Vol. 12 (2009); 2; pp. 1-33
Bates, Karl T.; Falkingham, Peter L.: Estimating maximum bite performance in Tyrannosaurus rex using multi-body dynamics. Biology Letters, Vol. 8 (2012); 4; pp. 660-664
Brochu, Christopher A.: Osteology of Tyrannosaurus rex: Insights from a Nearly Complete Skeleton and High-Resolution Computed Tomographic Analysis of the Skull. Memoir (Society of Vertebrate Paleontology), Vol. 7 (2003); pp. 1-138
Coria, Rodolpho A.; Calvo, Jorge O.: New Specimen of Giganotosaurus carolinii (Coria & Salgado, 1995), supports it as the largest Theropod ever found. Gaia, Vol. 15 (1998); pp. 117-122
Coria, Rodolpho A.; Currie, Philip J.: A new carcharodontosaurid (Dinosauria, Theropoda) from the Upper Cretaceous of Argentina. Geodiversitas, Vol. 28 (2006); 1; pp. 71-118
Holtz, Thomas R.; Molnar, Ralph E.; Currie, Philip J.: Basal Tetanurae. In: Weishampel, David; Dodson, Peter; Osmólska, Halszka: The Dinosauria. Berkeley (2004); pp. 71-110
Hutchinson, John R.; Bates, Karl T.; Molnar, Julia; Allen, Vivian; Makovicky, Peter J.: A Computational Analysis of Limb and Body Dimensions in Tyrannosaurus rex with Implications for Locomotion, Ontogeny, and Growth. Vol. 6 (2011); 10; pp. 1-20

With this taken into consideration, I think it's reasonable to conclude that Sue and Scotty were very similar in weight to MUCPv-Ch1, and the latter outweighed many Tyrannosaurus specimens quite a bit. Going by this, it's also highly likely that Tyrannotitan, Mapusaurus, and Carcharodontosaurus could seize the top spot as well; they could very well be >7.3 tonnes.

And you conveniently chose to make sure your quote doesn’t show that the post is from 2013→, or the multiple posts I’ve made since then clearly stating that I think their density should be similar.

Quit the nitpicking. When you choose to quote me for something, then don’t quote a post I made almost 7 years ago and that I have informed you before is outdated.

[dinosauria101]

Oh, oops! My bad!

Where did you say the density would be similar? I have no trouble believing this, but where was it?

[Ceratodromeus]

It helps if you actually read everything someone says on a subject if you are going to use them as a crutch in your argument.

[dinosauria101]

I am simply unaware of where it has been said that the same densities should be used.

If the same densities should be used, it depends on which specimens we use against which

[Verdugo]

Jan 22, 2020 16:03:36 GMT 5 dinosauria101 said:

Well, Horner and Paidan (2004) disagree with you there; they state Tyrannosaurus to be virtually full grown between 15 and 18 and this is consistent with some specimens such as B-rex.

'Virtually fully grown' and 'fully grown' are different things. None of T-rex specimens in Horner 2004 are actually fully grown, clearly stated so in the study:

According to these estimates, a virtually fully grown T.
rex would have been between 15 and 18 years old. (However, as the femur of MOR 1152 shows, growth can drop
more precipitously than an incremental estimate suggests.)
We have not found in any sectioned T. rex tibia or femur
evidence of an outer acellular, nearly avascular layer similar
to the external fundamental system (EFS) (Cormack
1957), that indicates effective cessation of growth. (An
EFS has been identified in the ornithischian dinosaur
Maiasaura (Horner et al. 2000).) The absence of an EFS in
preserved specimens of T. rex could suggest that none of
the animals had stopped growing,although growth was
greatly slowing. Without an EFS, the near cessation of
growth seems the most practical indicator of full size

Horner (2004) concluded that the T-rex specimens were nearly fully grown because the outermost cyclical growth marks (CGMs) aka growth rings are thinner, which suggests the growth has been slowing down significantly. They also suggested that the presence of EFS is not necessary when determining if the animals are fully grown.

However, Woodward et al 2020 (Horner also co-authored this study) disagreed with the proposition in Horner 2004.

However, annual zonal thicknesses between CGMs deeper within the cortices of BMRP 2002.4.1 (Fig. 4A) and BMRP 2006.4.4 (Fig. 4B) are variable, and zones do not consistently progress from widely spaced within the inner cortex to more closely spaced in the outer cortex. Because of unpredictable spacing within the cortex, reduced zonal thickness near the periosteal surface is likely an unreliable indicator of skeletal maturity in BMRP 2002.4.1 and BMRP 2006.4.4. Variable zonal thicknesses are, thus, likely to be observed in ontogenetically older T. rex individuals. To test this hypothesis, we examined femur and tibia thin sections from T. rex specimens USNM PAL (National Museum of Natural History) 555000, MOR (Museum of the Rockies) 1125, MOR 1128, MOR 1198, and CCM (Carter County Museum) V33.1.15. In all individuals, variability in annual zonal thicknesses was observed. In particular, compared to zone spacing within the mid-cortex, noticeably thinner zones are present within the innermost cortex of USNM PAL 555000 (Fig. 4C) and MOR 1128 (Fig. 4D). These results contradict the mathematically predictable zonal spacing in T. rex long bones reported by Horner and Padian (5), which used some of the same specimens reassessed in the present study. Results further suggest not only that BMRP 2002.4.1 and BMRP 2006.4.4 had not yet entered the accelerated growth period proposed for this taxon (4, 5) but also that the accuracy of the generalized T. rex body mass curve from Erickson et al. (4) would be affected by undetected individual variation in annual growth.

Regardless of cause, unpredictable CGM spacing observed here and in previous studies stresses caution when inferring relative maturity based on cortical LAG spacing (19). The observation of closely spaced CGMs within the innermost cortices of larger T. rex validates our interpretation that the thin zonal spacing observed in the outermost cortices of BMRP 2002.4.1 and BMRP 2006.4.4 are not reliable indicators of relative maturity when an EFS is absent.

They also pointed out that reduction of zonal thickness near the periosteal surface may be caused by the lack of resources (which causes its growth to slow down significantly), rather than an indicator of skeletal maturity

Similar instances of a single hiatus represented by narrowly spaced LAGs are reported in other tyrannosauroids (15). If this grouping of CGMs instead represents 6 years of protracted growth, then BMRP 2006.4.4 demonstrates the extent to which these individuals could adjust growth rate based on resource availability, in this case prolonging the ontogenetic duration of BMRP 2006.4.4 as a mid-sized carnivore.

Btw, BMRP 2006.4.4 is estimated to be 15+ years old, and is stated to be 'immature' and 'not yet entered the accelerated growth period'

On the basis of femur CGM count, BMRP 2002.4.1 was >13 years old at death, which is 2 years older than the original estimate by Erickson (8) based on fibula CGM count. The slightly larger BMRP 2006.4.4 was >15 years old.

Thus, histology supports morphological observations that BMRP 2002.4.1 and BMRP 2006.4.4 were skeletally immature individuals at death (10).

Results further suggest not only that BMRP 2002.4.1 and BMRP 2006.4.4 had not yet entered the accelerated growth period proposed for this taxon (4, 5) but also that the accuracy of the generalized T. rex body mass curve from Erickson et al. (4) would be affected by undetected individual variation in annual growth.

The study suggests that a 15+ years old T-rex still has more growing to do. Considering the size and morphology differences between a 15-16 years old T-rex to an older T rex like Sue or Scotty, i don't see any reasons to suggest a 15-16 years old T-rex to be fully grown adult. They may be sexually matured but clearly still have quite some ontogenic developments to go. 'Sexual maturity' only means that the animal is capable of reproducing but it does not say a lot to the size potential of an adult animal in its prime. For example, a sexually matured boar Brown bear is about the size of a sow, but an adult Boar in its prime is about 2x the size of a sow.

I was about to talk about the density too cause i don't see anywhere in literature (even in those cited by Theropod) suggesting a density of 0.8 kg/l for T-rex but it's good to see the man spoke up for himself. Also, it's important to be cautious about comparing density value from this study to density value from that study due to differences in methodology assumptions. I would love to see Theropod's up-to-date opinions on this.

Btw, what's the point of this density discussion? Why did you even bring it up in the first place? If you're interested in the technical side of science, sure, that's all good but i doubt that was your intention cause you're clearly more interested mounting some advantages for Giganotosaurus. Care to explain why it would be more advantageous to have higher body density cause i can't see any? All i can see is that having lower density will only make the animal lighter and more fleet footed without compromising its muscular strength. The end result is that the animal will be more agile, athletic, and powerful for its size. Also, Theropod's post (if it's still up-to-date) seems to indicate more advanced/extended air-sack system in T-rex too so that would mean more advantageous respiratory system.

[dinosauria101]

I didn't imply higher/lower densities would be advantageous as fight attributes. Density only has to do with body mass; a bit more stamina may result from the extra air sacs, but it likely wouldn't be THAT much.

As previously stated, the winner really depends on which specimens are matched against which.

[Ceratodromeus]

Jan 26, 2020 16:14:07 GMT 5 dinosauria101 said:

I am simply unaware of where it has been said that the same densities should be used.

this line literally does nothing in response to what i said. Do you just respond to respond or what? Go look into what someone has actually further said if you're going to use them as a crutch. it's really simple. He even linked to the post from 2013 he was talking about; that you omitted conveniently. Pay attention.

[dinosauria101]

Missed that, my bad.

As previously stated, if we're going to use the same densities than it depends on which specimens are matched with which. Some Tyrannosaurus specimens would win to the 2 Giganotosaurus specimens, some would be about 50/50, and some would lose.

[spartan]

Jan 26, 2020 20:01:50 GMT 5 dinosauria101 said:

I didn't imply higher/lower densities would be advantageous as fight attributes. 

Do you even read your own statements?

As previously stated, if we're going to use the same densities than it depends on which specimens are matched with which. 

[dinosauria101]

Jan 27, 2020 3:52:03 GMT 5 spartan said:

Jan 26, 2020 20:01:50 GMT 5 dinosauria101 said:

I didn't imply higher/lower densities would be advantageous as fight attributes. 

Do you even read your own statements?

As previously stated, if we're going to use the same densities than it depends on which specimens are matched with which. 

I was referring to masses when I said that.

[Infinity Blade]

Oh, oops! My bad!

I was thinking of not responding to this (evident by the fact that I'm only responding now), but I'm just so baffled. It's one thing if you don't notice the date in which a post was first written or last edited (though, these honestly aren't all that hard to see). But shouldn't you have noticed that this post of theropod's that you quoted was on page 26 of 84? How come that didn't scream out "Old post!" to you?

[dinosauria101]

Jan 27, 2020 5:00:08 GMT 5 Infinity Blade said:

Oh, oops! My bad!

I was thinking of not responding to this (evident by the fact that I'm only responding now), but I'm just so baffled. It's one thing if you don't notice the date in which a post was first written or last edited (though, these honestly aren't all that hard to see). But then you somehow missed the fact that this post of theropod's that you quoted was on page 26 of 84? How come that didn't scream out "Old post!" to you?

I meant that I didn't mean to misrepresent what he was saying when I said that

[Infinity Blade]

?

theropod didn't call you out for misrepresenting what he was saying. He called you out for quoting a comment of his that's 7 years old and clearly doesn't reflect his views now.

[jdangerousdinosaur]

Jan 27, 2020 5:08:33 GMT 5 Infinity Blade said:

?

theropod didn't call you out for misrepresenting what he was saying. He called you out for quoting a comment of his that's 7 years old and clearly doesn't reflect his views now.

This is something else i and countless others have brought up to him that he refuses to stop doing. Using older and outdated data its really not a good idea to do this because things change very quickly within palaeontology.